The present invention is directed toward the field of radio telemetry. In particular, an improved radio modem is disclosed for use in an autonomous radio telemetry system, the radio modem including a programmed mode of operation that converts the general purpose radio modem into a special purpose radio telemetry computer system, thereby eliminating the need for a separate telemetry computer as taught by the prior art.
In a telemetry system analog or digital metering data, such as an analog measurement of a process variable, or the digital state of a switch, is captured at a remote location by a telemetry computer and is then transmitted to a central computer facility via a telecommunication device. In radio telemetry the telecommunication device is a radio modem that transmits the metering data between the telemetry computer and the central computer facility via radio frequency waves, thus eliminating the need for land-line wiring, such as a telephone line.
Applications for telemetry systems range from simple switch actuation and monitoring systems to complex process line computers. For example, the following systems could be implemented with an autonomous telemetry system: (i) monitoring a door switch and sending a signal when the door is opened; (ii) counting the number of items put into a drop box, by noting the number of times the drop box door is opened, and periodically reporting the number of items in the box; (iii) acquiring and recording the temperature and current draw of a motor and transmitting recently recorded data when the temperature of the motor exceeds a predetermined level; or (iv) remotely turning on/off lights, or an alarm system; etc. The applications of such telemetry systems are numerous, and the previous examples are merely presented to assist in understanding the broad scope of the possible applications for such telemetry systems.
Prior art radio telemetry systems include a separate telemetry computer and radio modem at a remote location for capturing and transmitting data to the central computer facility. Implementors of these types of systems incorporate an embedded programmed microprocessor as the telemetry computer, and interface the telemetry computer to input/output devices such as a complex analog to digital converter board, or a simple switch. The telemetry computer is also connected to the radio modem, generally via a serial interface. The telemetry computer controls and monitors the interface to the input/output devices and communicates with the central computer system using the radio modem. In these types of prior art telemetry systems, the radio modem is simply a module in the overall remote telemetry sub-system that is required for communication purposes.
These previous telemetry systems suffer from a number of disadvantages, particularly when the telemetry system is used in a relatively simple application, such as the monitoring of a switch, or the acquisition of a single process variable. The disadvantages of these prior art systems include high cost, high power consumption, large physical size, and complex integration.
These disadvantages arise because the previous telemetry systems do not appreciate or utilize the power of the microprocessor or microcontroller that is built into present day radio modems. Instead, these systems use the radio device solely for communication, and employ a separate embedded microprocessor, the telemetry computer, as the interface to the input/output devices. These systems waste the processing power available in the radio modem and therefore result in increased cost, power, and size of the telemetry device.
Therefore, there remains a need for a simple, low cost, small, and easy to integrate telemetry device for use in an autonomous radio telemetry system. There remains a further need for such a telemetry device that does not waste the processing power inherent in the radio modem, but instead is configured to maximize the processing power of the microprocessor contained in the radio.
In addition, there remains a need for an autonomous telemetry system that includes at least one of the above mentioned telemetry devices in communication with a central computer system that is capable of sending commands to the telemetry devices, and receiving data transmissions from the telemetry devices indicating the state of input/output devices at the remote location.